In the streets, crowd-estimating experts say, there probably were somewhere between 250,000 and 450,000 people. You can add another 50,000 who were at CenturyLink Field, and 27,000 at Safeco Field; more precise figures because people actually are counted at these venues.

That still may make it the biggest party in the city’s history.

The street-crowd numbers are from experts who deal in estimating these things by doing real analysis, not guesswork.

A 700,000 crowd estimate is nearly a fifth of the entire population of King, Pierce, Snohomish and Kitsap counties.

“There is civic pride that goes into estimating these numbers. They tend to be overstated wildly,” says Steve Doig, the Knight Chair in Journalism at Walter Cronkite School of Journalism and Mass Communication at Arizona State University, who has covered the subject of crowd estimation.

“Or maybe it’s from a cop who looks around and says, ‘My God, there must be 700,000 people here.’ ”

Once, in the heyday of Seattle’s Seafair hydroplane races, there were wild estimates of how many thousands of fans were out there.

Pat Cashman, longtime Seattle radio and TV personality, remembered how, when three local TV stations covered the races in the 1980s, there were estimates of 300,000 or more attending the race at Lake Washington.

He said (as quoted in a story last summer), “Doing the math, among three TV stations all providing live coverage, that left only about 28 people actually available to watch on TV.”

Seattle police say that the figure of 700,000 for the Seahawks parade, although used in their blotter postings, didn’t really come from them but from “professional parade organizers.”

That would be Seafair.

Melissa Jurcan, director of sales, marketing and communications for Seafair, says “we work with” the city in figuring out a crowd estimate.

And how was that arrived at?

“It’s not an exact science,” says Jurcan. She says it’s based on years of running an event such as the annual Torchlight Parade and on “eyeball” analysis.

Jurcan also says that based on calling hotels, condos and restaurants, and just looking at people watching from tops of buildings, an additional 300,000 people were watching who were not in the streets. That would bring the total to 1 million.

Well.

“When I read those kinds of numbers, I kinda giggle. You don’t have enough room in downtown Seattle to get a million people,” says Butch Street, who counts crowds for a living.

He is in charge of public-use statistics for the National Park Service. He works out of Denver, so make of that what you will. “If you want, you can quote me as saying there were only 14 people there,” he says.

Presidential inaugurations, gatherings at the Washington Monument, he’s the guy who gives the official estimate.

Street uses satellite images and photos taken from a helicopter, and spends hours with a magnifying glass to get crowd estimates.

He’s the one who got into controversy when he said that Louis Farrakhan’s Million Man March in 1995 actually had 460,000 marchers.

Farrakhan was not pleased.

“I told him, ‘Louis, you should have named it the 500,000 Man March, and you’d have had the fifth-largest march in Washington (D.C.).’ Five hundred thousand is still a lot of frigging people,” says Street.

Both Street and Doig were emailed overhead photos of the Seahawks parade.

Street estimates that the half of the crowd closest to parade had each person occupying 2½ square feet. The other half of the crowd, he estimates, had each person occupying about 5 square feet.

Doig says that the 2½-square-foot figure would mean people literally could not move.

He prefers to use an estimate of 5 square feet for one half of the crowd, and 7½ square feet per person for the other half.

Albert Gonzales, a geographical information systems analyst with Seattle Public Utilities, did some computer work with the parade route and the cross streets along the route.

On the cross streets, he had the crowds 125 feet deep each way. On the route itself, he left 12 feet for Seahawks vehicles to pass through.

He also counted space on each side of the north parking lot of CenturyLink Field. The parking lot itself was not counted as the people who went there were overflows from the streets as the lot was opening later.

The result was about 1.5 million square feet.

Using Doig’s numbers, the crowd estimate is 250,000.

Using Street’s numbers, the estimate is 450,000.

You decide whether you think there were 300,000 people in the buildings watching the parade, as Seafair says.

A density report says 200,000 people work in all of downtown Seattle.

Street says he hears all the time from people who don’t believe his lowball numbers.

“You’re never going to win. It’s all perception. You could be in the middle of a football stadium and it could look like a million people, not 76,000 people,” he says.

Says Doig, “People make … guesses, and then the guesses get enshrined in history. You start out with a fantasy, and it just grows and grows.”